Are Your Herbal Supplements Safe?

We sort out the scary headlines and scams

It's been a rough few years for herbs. A Canadian study published late last year found that of 44 herbal products tested, many were adulterated or mislabeled. The study authors said that two samples of echinacea contained a weed that could interact with certain medications; a sample of St. John's wort was actually an herbal laxative; and a bottle of ginkgo biloba was contaminated with black walnut, which theoretically could put people with nut allergies at risk. In December, the FDA yanked one herbal supplement from the shelves after it was linked to dozens of cases of liver failure. And a supplement manufacturer who was jailed for selling a weight loss supplement that turned out to contain a toxic chemical is facing new charges over sketchy products he was churning out, even as he was waiting to enter prison.

Though centuries of traditional use and scientific studies point to the therapeutic effects of many medicinal herbs, herbal supplements have always had a potential dark side. Their manufacture isn't regulated as tightly as that of drugs, creating opportunities for modern-day snake oil salesmen to make a quick buck.

There's more to the recent exposes and scandals than most media outlets reported. A month-long investigation by Prevention found that the many recent headlines—including "Supplements Are Often Not What They Seem" in the New York Times—emerged from a seriously flawed study. And in the other cases, when supplements were exposed as dangerous, the offending ingredients were not the herbs but other chemicals introduced during manufacture.

Fans of herbs shouldn't go dancing blithely through yellow fields of St. John's wort quite yet, however. Our probe also spotlighted the need to be savvy about using herbal remedies and rendered an especially harsh verdict on products promising weight loss, a metabolism boost, or the like. Pills marketed to whittle your middle are seductive, we know. (Oh, do we know.) But given that they either don't work or may work via chemicals that are dangerous to your liver and your life, the only advice we have is, well, run far, far away.

Here's what we learned—and what you need to know.

The Shout from Canada
To arrive at their explosive finding that herbal remedies—or at least the 44 products they tested—may contain little, if any, of the herb on the label and are often contaminated with other substances, researchers at the University of Guelph in Ontario used a technique called DNA barcoding, developed at their institution (just see our previous report in Is Your Supplement A Fake?). DNA barcoding identifies a species using a small segment of DNA, much like the bar code on a grocery product identifies it at the checkout scanner. "Most of the products tested were of poor quality," wrote coauthor Steven G. Newmaster, PhD, herbarium director at the university's Center for Biodiversity Genomics.

What's more, the researchers said, they discovered "considerable product substitution, contamination, and use of fillers," including rice, wheat, and ground soybeans. But many experts question the findings of this study for several reasons. For one thing, for DNA barcoding to be reliable, you need a fairly complete database of already-identified DNA samples for comparison. That currently doesn't exist, says Andrea E. Schwarzbach, PhD, an associate professor in the department of biomedicine at the University of Texas at Brownsville. Another problem is that the test can locate the herbs only if the DNA is still present. But many herbal supplements contain extracts with molecules of the plant's therapeutic phytochemicals that may not carry any plant DNA but can still be fully potent, says Paul M. Coates, PhD, director of the Office of Dietary Supplements at the National Institutes of Health.

The study also didn't follow set scientific standards. The researchers should have conducted their DNA test on one group of supplements, and then tested two identical groups of those supplements via recognized ID methods, such as microscopic and chemical testing. This is the gold standard for a quality medical study—the randomized controlled trial.

Finally, DNA barcoding technology is a product of the Canadian Centre for DNA Barcoding, which is affiliated with the Biodiversity Institute of Ontario. The study's coauthor, Dr. Newmaster, is director of BIO's herbarium—which means that the researchers who tested the technology work for an organization that potentially profits from its use. Their paper, in fact, suggests that the supplement industry embraces the technology to authenticate ingredients. Dr. Newmaster and his coauthor did not respond to requests for an interview.

A Dark Side Remains
Even if the alarming University of Guelph study was faulty, the truth is, problems do exist. Some remedies contain less herb than claimed, says Tod Cooperman, MD, president of ConsumerLab.com, an independent company that tests supplements. Others may be contaminated with heavy metals, he adds.

As it stands, there's no guarantee that you get what you pay for. Good news: Experts agree that most herbal supplements are at least safe.

Where women and young men get into big trouble, says Robert Bonakdar, MD, director of pain management at the Scripps Center for Integrative Medicine in La Jolla, CA, is in the realm of quick fixes—weight loss, revved metabolism, sports/muscle/performance enhancement. There, your chances of buying a suspect product are higher. Fall for this lure and you might lose not only your cash but also your liver—possibly even your life.

In the 2013 case involving OxyElite Pro, a "fat-burning" supplement containing the herb Rauwolfia canescens, the FDA notified USPLabs that its product was linked to dozens of cases of nonviral hepatitis and liver failure. Used in herbal medicine to treat high blood pressure, rauwolfia was one of at least seven ingredients in the product.

Here's where the wheels come off the cart. Traditionally, rauwolfia has never been used for weight loss, and there's no evidence to suggest it's effective for shedding pounds. The product also contained the stimulant DMAA, for which none of the required safety evidence was presented to the FDA. After receiving the FDA's notification, USPLabs voluntarily destroyed some 22 million dollars' worth of product.

Last summer, Walmart.com stopped selling Craze, a preworkout supplement, after the US Anti-Doping Agency discovered that it contained traces of methamphetamine-like substances. Craze's manufacturer claimed that the active ingredient was derived from dendrobium orchid, a traditional Chinese medicine known as Shi-Hu. (Its effects haven't been clinically tested.) There's no evidence that Shi-Hu contains the implicated substances; it's more likely that other chemicals added to Craze, not the herb, got it pulled from the market.

Your Liver Hates This Stuff
"Women are often shocked when they end up in the ER and need urgent care for serious liver problems, especially when we trace the liver damage back to the 'herbal' weight loss pills they were taking," says Herbert L. Bonkovsky, MD, a professor of medicine at Carolinas HealthCare System in Charlotte, NC, and the University of North Carolina at Chapel Hill. "They thought they were taking a safe, natural supplement that would magically help them shed pounds. Instead, it damaged their liver and made them deathly ill. Some have required liver transplants or have died."

Even when something innocuous, like green tea, is listed as the main ingredient, shape-shrinking products are bad news. "Read the claims," says Daniel Fabricant, PhD, who runs the FDA's division of dietary supplements. "If they seem too good to be true, they probably are."

Shopper's Guide1. Find a referee
"If your herb-wise health care practitioner recommends a brand that's been clinically tested, it's unlikely to be of poor quality," says Robert Bonakdar, MD, director of pain management at the Scripps Center for Integrative Medicine in La Jolla, CA. Not all MDs know about herbs, but integrative medicine docs often do. Naturopaths (NDs), degreed by 4-year institutions such as Bastyr, study botanical medicine. Herbalists who pass the American Herbalists Guild test have the RH (AHG) designation. Some licensed acupuncturists are also credentialed to practice with Chinese herbs.

2. Give it time
Except for remedies like echinacea for colds and ginger for nausea, most herbs "won't cure anything overnight—they're more like a gentle nudge to your system," says Prevention advisor Kevin Spelman, PhD, distinguished lecturer at the Maryland University of Integrative Health. Plan on consistent use for 1 to 3 months to experience benefits. Learn more on the University of Maryland Medical Center's website. Check that the supplement passed testing on consumerlabs.com ($36 annually).